This seems like it's devolving into a semantics discussion, but I would argue that playersexuality is when the LI's sexuality is either vague enough that one assumes that they are whatever sexuality they would need to be to romance your PC -OR- when they actively change from straight to gay based on your player's PC.
In this case, the second is out because this never happens in Bioware games. If you want a good example of this, check out the text-based games by "Choice of Games" (for iOs, Android, and web-platforms). In those, there are often characters who will change their gender and sexuality to fit the needs of the PC. For example, if a PC identifies themselves as male and straight, then the character would be a straight female named Ashley. If the PC identifies as a male and gale, then the character would be a gay male named Ashton. One of them even has the option to randomly assign gender to each of the LI's so each playthrough will give you different options. However, this doesn't happen at all in Bioware games.
In the case for the first, it could have been construed that Merrill and Fenris were "playersexual" since neither explicitly identifies as gay, straight, or bisexual. However, context clues suggest that they aren't completely 'ambiguous'. I've always seen them as more reserved (i.e. private) bisexuals who don't feel the need to outwardly identify their sexuality. I'm not surprised that Gaider WoG'd that they are bisexual since he's hinted as much in the past.
Either way, I suspect that they are not going to be going back to the "ambiguous" sexuality in DA: I. They seem pretty happy with clearly defined sexualities this time around.
ETA: Dammit. I got distracted and took too long posting this and now there are like a dozen posts since. Grr. Apologies if it's not still relevant.